I'm not sure I buy this. Reading a book for example, you always read a book linearly. When I'm reading code I'm looking for different details at different times

I'm not sure I buy this. Reading a book for example, you always read a book linearly. When I'm reading code I'm looking for different details at different times, I'm doing a lot of scanning. Sometimes it's functions, other times variables, strings etc. but being able to scan only items in a particular colour really speeds up my search. Syntax highlighting really helps with this. I'm also not sure about the idea of trying to hold more code in your head. Over the last few years I've changed my practices so that I don't have to hold much information in my head. For me this is one of the key benefits of TDD for example. At this point I find context switching easy to do because I've externalised the majority of my process to tools and practices. If anything, good syntax highlighting makes code a real pleasure to read. Coming from java/eclipse(stock scheme) to ruby/textmate(vibrant ink) I was struck by how much I preferred reading the code in the bold colours of vibrant ink. Going back to java seemed dreary by comparison.